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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

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Tryon Creek Report Card

Photo of Tryon Creek

This is a summary of conditions in the Tryon Creek Watershed based on 2015 data from the Watershed Health Index. The scores are a snapshot of conditions across the entire watershed. Conditions can vary in smaller parts of the watershed.
Link to introduction page on the watershed report cards

Learn more about the Tryon Creek
Watershed Program and Projects


Tryon Creek Hydrology Score: B

Hard surfaces like roads, rooftops and parking lots in this watershed create a lot of stormwater runoff when it rains. Stormwater makes stream banks unstable, causes erosion and deposits sediment in streambeds. Runoff from Interstate 5, SW Barbur Boulevard and other streets carries pollutants into streams. New stormwater management projects at the Oregon Department of Transportation Baldock Maintenance Yard, the Barbur Boulevard Park and Ride and I-5 at SW 26th that manage runoff from nearly 30 acres are the start of improving the impervious area score.

About 30 miles of streams flow through the watershed, and about three miles of stream are in pipes. Environmental Services continues to plan projects in this area to restore stream conditions, including bringing some of those piped streams back to the surface.

Tryon Creek
Hydrology Average Score

Hydrology score: 6.0

6.0

What is this?
Effective impervious area
Effective impervious area: 5.2
5.2
What is this?
Stream connectivity
Stream connectivity: 6.8
6.8

Tryon Creek Water Quality Score: B

Despite rich stream and habitat resources, substandard water quality limits the overall health of the watershed. E. coli bacteria levels often exceed water quality standards, probably because of sewage leaks and animal waste.

Suspended solids and pollutants that bind to solids are a problem that comes from stormwater runoff. Silt and sediment from roads and development accumulate in Tryon Creek. Copper from automobile brake pads is a common pollutant that is harmful to salmon. And in summer, stream temperatures rise above levels needed for salmon rearing.

Ongoing projects to remove invasive plants and restore native vegetation, protect habitat, restore streams and manage stormwater, like the Multnomah Village green streets, will help prevent further decline in water quality scores and lead to gradual improvement.

Tryon Creek
Water Quality Average Score

Water quality score: 6.1

6.1

What is this? Ammonia-nitrogen Ammonia-Nitrogen: 9.9
9.9
What is this?
Dissolved copper
Dissolved copper: 5.7
5.7
What is this?
Dissolved oxygen
Dissolved oxygen: 8.6
8.6
What is this?
E. coli
E. coli: 5.3
5.3
What is this? Temperature Temperature: 5.0
5.0
What is this?
Total mercury
Total mercury: 1.8
1.8
What is this?
Total phosphorus
Total phosphorus: 6.6
6.6
What is this?
Total suspended solids
Total suspended solids: 5.7
5.7

Tryon Creek Habitat Score: B

Habitat conditions vary across the watershed. The best conditions are in the Tryon Creek State Natural Area where the creek is fairly healthy. But more improvements are needed above and below the park.

Protected open spaces like the natural area contribute to good tree canopy and other habitat scores. Active community groups volunteer to remove invasive plants and restore native vegetation.

The low stream accessibility score is because of culverts that block fish access. Environmental Services and bureau partners are planning a project to replace the Boones Ferry Road culvert, which will improve fish passage to the upper portions of Tryon Creek.

Tryon Creek
Habitat Average Score

Tryon Creek Habitat score: 6.5

6.5

What is this? Bank condition (hardening) Bank condition: 10
10
What is this? Floodplain condition Floodplain condition: 10 10
What is this? Large wood Large wood: 4.8
4.8
What is this? Riparian integrity Riparian integrity: 6.9
6.9
What is this?
Stream accessibility  Stream accessibility: 1.5 1.5
What is this? Substrate composition Substrate composition: 2.3 2.3
What is this?
Tree canopy
Tree canopy: 10
10

Tryon Creek Fish and Wildlife Score: C-

Pacific lamprey, coho salmon and other native fish use Tryon Creek, but impassable culverts limit their abundance. Because of good conditions in the Tryon Creek State Natural Area, scores for aquatic insects and birds are fair, although insect species aren’t as diverse as they should be. That indicates we have more work to do to avoid further declines. More than 60 species of birds live in the Tryon Creek watershed for at least part of the year.

 

Tryon Creek
Fish and Wildlife Average Score

Tryon Creek Fish and wildlife score: C-

4.1

What is this? Birds Birds: 4.7
4.7
What is this?
Fish
Fish: 2.0
2.0
What is this?
Macroinvertebrates
Macroinvertebrates: 5.7
5.7

For more information about what we measure and where these scores come from, visit the About Watershed Report Cards page.

See some of what Environmental Services is doing for healthy rivers and streams on the Explore Portland’s Watersheds map.